Opto-electric hybrid modules are typically produced by: individually producing a flexible circuit board including an electric circuit provided on a surface of an insulation layer, and an optical waveguide including an under-cladding layer, a core and an over-cladding layer stacked in this order; bonding a back surface of the insulation layer of the flexible circuit board to a surface of the over-cladding layer of the optical waveguide with an adhesive agent; and mounting an optical element on a predetermined portion (mounting pads) of the electric circuit. The opto-electric hybrid module is flexible, and is advantageous for use in a bent state in a small space and for use in a movable portion such as a hinge portion to meet a recent demand for size reduction of electronic devices and the like.
An opto-electric hybrid module as shown in a transverse sectional view of FIG. 5 (see, for example, PTL1) is proposed, which includes an electric circuit 4 provided directly on a surface of an over-cladding layer 13 of an optical waveguide W1 (without provision of an insulation layer) for simplification of the production method thereof. The optical element 5 is mounted on a predetermined portion (mounting pads 4a) of the electric circuit 4. In FIG. 5, a reference character 11 designates an under-cladding layer of the optical waveguide W1, and a reference character 12 designates a core of the optical waveguide W1.
In the opto-electric hybrid module, the elastic moduli of the under-cladding layer 11 and the over-cladding layer 13 are each set at a low level for improvement of the bending resistance of the module.